1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus for forming an image on a recording medium, and a unit removable from the electrophotographic image forming apparatus.
2. Description of the Related Art
An electrophotographic image forming apparatus forms an image on a recording medium (such as a recording sheet or an OHP sheet) by using an electrophotographic image forming method. Examples of the electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (such as a laser beam printer and a LED printer), a facsimile machine, and a word processor.
A unit refers to a cartridge which is removable from the body of the electrophotographic image forming apparatus. The cartridge is an integral structure of an electrophotographic photosensitive drum and at least one of a processing unit, a charging unit, a developing unit, and a cleaning unit. A unit also refers to, for example, a single electrophotographic photosensitive drum, a processing unit, or a fixing unit, which is removable from the body of the electrophotographic image forming apparatus.
In the past, an electrophotographic image forming apparatus performing an electrophotographic image forming process has used a cartridge method which allows a process cartridge (serving as a unit) having an electrophotographic photosensitive member and a processing unit (which acts on the electrophotographic photosensitive drum) integrally formed with each other to be removable from the body of the image forming apparatus. When such a cartridge method is used, the apparatus can be maintained by a user without the help of a service personnel, so that the operability of the apparatus is considerably enhanced. Therefore, such a cartridge method is widely used in the electrophotographic image forming apparatus.
When the user replaces such a process cartridge, the user may replace the process cartridge by moving it in a way that is not necessarily conceived by the manufacturer. Therefore, a guide is disposed at the body of the image forming apparatus so that the process cartridge is mounted to the body of the image forming apparatus along a predetermined path.
However, when the process cartridge is mounted at an unexpected angle or with an unexpected mounting force, the process cartridge may not be properly mounted to the body of the image forming apparatus.
Therefore, a proposal for detecting whether or not the process cartridge or the like is properly mounted to the body of the image forming apparatus has been made.
For example, in Japanese Patent Laid-Open No. 9-160469, when process cartridges are all mounted to a tandem color image forming apparatus to which more than one process cartridge can be mounted, a detection circuit is formed via the process cartridges in order to detect the mounting of the process cartridges.
However, in the detection circuit, connection of contacts of the process cartridges and contacts of the apparatus body and connection of the contacts of the process cartridges that are adjacent to each other are achieved at the process cartridges at one end in a longitudinal direction. That is, strictly speaking, the mounting state of the process cartridges at the other end in the longitudinal direction and the state of connection of drive members of the apparatus body and drive members of the process cartridges are not detected.